Apparatus for distinguishing living body fingerprint and method thereof

Abstract

An apparatus for distinguishing living body fingerprint from artificial fingerprint and a method thereof are provided. A living body recognition unit determines whether fingerprint in question is living body fingerprint or not, based on the unique color of the living body fingerprint and a change of the fingerprint color which is caused due to a change of contact pressure when the living body fingerprint is contacted with the fingerprint input window. A fingerprint recognition apparatus computes color information from the fingerprint image acquired by the color image sensor, and color change information based on the change of contact pressure, and determines whether the fingerprint in question is the living body fingerprint by determining whether or not the computed color information meets a reference color range and/or if the color change information meets a reference condition.

1 . A method of distinguishing a living body fingerprint, comprising:
 irradiating a light toward a prism and acquiring a color fingerprint image of a contacting fingerprint contacted with a fingerprint input window of the prism; and   determining the contacting fingerprint to be the living body fingerprint, if the color fingerprint image has a change of color at a first and second time points, the contacting fingerprint being in contact with the fingerprint input window at the first and second time points.   
   
   
       2 . The method of  claim 1 , wherein the determining comprises:
 computing color change information regarding a change of color information of the color fingerprint image at the first and second time points, the contacting fingerprint being in contact with the fingerprint input window at the first and second time points; and   determining the contacting fingerprint to be the living body fingerprint, if the color change information meets a reference condition regarding a change of color of the living body fingerprint which is caused in accordance with a change of a contact pressure.   
   
   
       3 . The method of  claim 2 , wherein one of the first and second time points corresponds to a time point when acquiring of the color fingerprint image begins according to the contact of the fingerprint against the fingerprint input window. 
   
   
       4 . The method of  claim 2 , wherein the reference condition corresponds to at least one of ΔG>ΔR, ΔG>ΔB and R(1)−G(1)>R(2)−G(2), where R(1) and G(2) correspond to lightness of red and green components of the color fingerprint image at the first time point, R(2) and G(2) correspond to lightness of red and green components of the color fingerprint image at the second time point, ΔR=R(2)−R(1), ΔG=G(2)−G(1), and ΔB is a difference of lightness of blue component of the color fingerprint image at the second and first time points. 
   
   
       5 . The method of  claim 2 , wherein the color information includes lightness levels of the red, green and blue components. 
   
   
       6 . The method of  claim 2 , further comprising determining whether or not color information at one time point of the plural time points comprising the first and second time points, or an average of color information at two or more time points of the plural time points comprising the first and second time points, falls to a reference color range, and if not, determining the contacting fingerprint to be artificial fingerprint and omitting the computing of the color change information and the determining the contacting fingerprint to be the living body fingerprint. 
   
   
       7 . The method of  claim 6 , wherein the reference color range spans from a color acquired from the living body fingerprint at one time point of the plural time points comprising the first and second time points to a color added with a predetermined margin of the acquired color, or from an average of colors acquired from the living body fingerprint at two or more time points of the plural time points comprising the first and second time points to a color added with a predetermined margin of the average of colors. 
   
   
       8 . The method of  claim 2 , wherein the color information is based on a ridge area of the color fingerprint image. 
   
   
       9 . A method of distinguishing a living body fingerprint comprising:
 irradiating a light toward a prism and acquiring a color fingerprint image of a contacting fingerprint contacted with a fingerprint input window of the prism;   computing color information of the acquired color fingerprint image; and   determining whether or not the computed color information falls to a reference color range of the living body fingerprint, and if so, determining the contacting fingerprint to be the living body fingerprint.   
   
   
       10 . The method of  claim 9 , wherein the color information is based on a ridge area of the color fingerprint image. 
   
   
       11 . An apparatus for distinguishing a living body fingerprint, comprising:
 a light refractor comprising a fingerprint input window with which fingerprint is contacted;   a light source to irradiate light to the light refractor to acquire an image of the fingerprint;   an optical lens system to converge the image output from the light refractor;   a color image sensor to acquire a color fingerprint image from the image converged on the optical lens system; and   a living body recognition unit to compute color change information regarding a change of the color information of the color fingerprint image being acquired at a first and second time points, and determine the fingerprint to be the living body fingerprint when the color change information meets a reference condition regarding the change of color of the living body fingerprint, wherein the fingerprint is in contact with the fingerprint input window at the first and second time points.   
   
   
       12 . The apparatus of  claim 11 , wherein one of the first and second time points corresponds to a time point when acquiring of the color fingerprint image begins according to the contact of the fingerprint against the fingerprint input window. 
   
   
       13 . The apparatus of  claim 11 , wherein the reference condition corresponds to at least one of ΔG>ΔR, ΔG>ΔB and R(1)−G(1)>R(2)−G(2), where R(1) and G(2) correspond to lightness of red and green components of the color fingerprint image at the first time point, R(2) and G(2) correspond to lightness of red and green components of the color fingerprint image at the second time point, ΔR=R(2)−R(1), ΔG=G(2)−G(1), and ΔB is a difference of lightness of blue component of the color fingerprint image at the second and first time points. 
   
   
       14 . The apparatus of  claim 11 , wherein the color information includes lightness levels of the red, green and blue components. 
   
   
       15 . The apparatus of  claim 11 , wherein the living body recognition unit determines whether or not color information at one time point of the plural time points comprising the first and second time points, or an average of color information at two or more time points of the plural time points comprising the first and second time points, falls to a reference color range, and if not, determines the fingerprint to be artificial fingerprint and omits the determining of the living body fingerprint based on the color change information. 
   
   
       16 . An apparatus for distinguishing a living body fingerprint, comprising:
 an optical refractor comprising a fingerprint input window with which a fingerprint is contacted;   a light source to irradiate light to the optical refractor to acquire an image of the fingerprint;   an optical lens system to converge the image being output from the optical refractor;   a color image sensor to acquire a color fingerprint image from the image converged on the optical lens system; and   a living body recognition unit to compute color information of the color fingerprint image which is acquired by the color image sensor, and determines the fingerprint to be the living body fingerprint if the color information falls to a reference color range of the living body fingerprint.